Based on the traditional single-phase OBC topology, a unified operation has been achieved of charging (G2V), discharging (V2G), and harmonic and reactive power compensation at the point of common coupling, through power device reuse and control strategy optimization without adding additional hardware. An equivalent continuous model of the system is established, with a harmonic and reactive power detection method designed based on SOGI-FLL. Furthermore, multi-frequency high-precision current compensation can be achieved with dual fractional-order fast repetitive control combined. Simulation results demonstrate that the proposed scheme can effectively suppress 5th to 15th harmonic currents, reduce THD, and improve voltage stability while ensuring bidirectional energy interaction, thus providing an efficient power electronic interface form for the integrated operation of “source-grid-load-storage” (SGLS).